The objectives of this study are to compare the prevalence of MIH in children seeking dental care spontaneously at the Department of Comprehensive Children's Dentistry of the University of Buenos Aires (UBA) and Department of Pediatric Dentistry of the University of La República (UdelaR) and to analyze the distribution according to year of birth, sex, age, number of affected teeth and maximum degree of severity in molars and incisors. During 2010, nine pediatric dentists from both schools (Kappa = 0.94) assessed all children born between 1993 and 2003 whose 4 first molars and 8 permanent incisors had erupted. Specially designed charts were used to record sex, year of birth, institution, presence of MIH, number of affected incisors and molars and maximum degree of severity for each tooth. Two groups were formed: UBA: A (n = 512) and UdelaR: B (n = 463).
Results: 975 children (11.6 +/- 2.67 years) were evaluated. The prevalence of MIH in the total sample was 6.56%, without significant differences between A and B (p = 0.76). There was no significant difference between groups regarding age (p = 0. 95) or sex (p = 0.30). A significant increase was found in both institutions according to year of birth during the study period. (A: p = 0.0017) B: p = 0. 0058).
Conclusions: The results of this study show a similar prevalence of MIH among patients seeking dental care at the Schools of Dentistry of the University of Buenos Aires (Argentina) and University of la República (Uruguay). No significant difference was found comparing the distribution by sex, affected teeth or severity of each tooth. A highly significant positive correlation was found regarding the year of birth. The relevance of MIH as an emerging pathology requires studies on larger samples covering the entire countries.